/*
    1、该文件是用于创建一个为Count组件服务的reducer,reducer的本质是一个函数
    2、reducer函数会接到两个参数，分别为：之前的状态preState，动作对象action
 */
import {INCREMENT, DECREMENT} from "./constant"

const initState = 0;

export default function countReducer(preState = initState, action) {
    console.log(preState, action)
    const {type, data} = action;
    switch (type) {
        case INCREMENT :
            return preState + data;
        case DECREMENT :
            return preState - data;
        default:
            return preState;
    }
}